1. Field of the Invention
The present invention relates to enclosed conductor bar systems. More specifically, the present invention provides a conductor bar system providing electrical power to moving equipment, having a trolley that may be installed or removed at any point in the conductor bar system.
2. Description of the Related Art
Presently existing conductor systems for moving equipment include trolleys that may only be safely installed or removed at either end of the track or in specially constructed track sections including a door.
Within a conductor bar system using door track sections, each door track""s section includes a pair of hinged doors in the bottom of the track, thereby permitting insertion and removal of trolleys. This design raises the issues of securely locking the doors, and accurately aligning the doors with the remainder of the track to form an uninterrupted track for the trolleys.
A typical plastic enclosed system includes a housing of extruded plastic, with the copper conductor bars encapsulated directly into the housing. Trolleys must be installed or removed from such systems only at one end of the track. If removal of the trolley from an end of the track is not possible, the only other alternative is to pry the track open, which raises safety concerns.
Accordingly, an enclosed conductor bar system having a trolley that may be installed or removed at any point along the track is desired. Such a system would result not only in ease of manufacture and installation, but also ease in reconfiguring an existing system as needs for the system change over time.
The present invention provides a continuously installable/removable collector trolley. The trolley includes a chassis on its upper portion, having a plurality of electrically conductive brushes, which are spring biased upward. The upper portion of the chassis also includes a plurality of selectively extendable and retractable bearing assemblies. The lower portion of the trolley includes a means for extending and retracting the bearing assemblies, a means for connection to a power cord, and preferably one or more pulling loops.
In one preferred embodiment of the trolley, four bearing assemblies are provided, corresponding to the four corners of the trolley. The lower portion of the trolley preferably includes at least one release lever for extending and retracting the bearing assemblies. A preferred embodiment includes one release lever for each pair of bearing assemblies at each end of the trolley, although other possible embodiments may include a single release lever for extending and retracting all four bearings, or a separate release lever corresponding to each bearing assembly. A preferred embodiment of the release lever is a pivoting release lever, having a peg mounted radially outward from its pivot axis. The peg is dimensioned and configured to fit within a slot within the bearing assembly, so that pivoting of the release lever will cause the peg to move the bearing assembly inward or outward. For example, a pair of pegs mounted 180xc2x0 apart may be utilized to enable one release lever to extend and retract a pair of bearing assemblies at one end of the trolley.
A typical bus section includes a housing with a plurality of conductor bars therein. An insulator may be provided between the conductor bars and the housing, with the bus bars retained within the insulator. The insulator is typically retained in the top of the housing. The bottom of the housing includes a shelf extending along each side, dimensioned and configured to permit the bearings to roll along it. The bottom surface of the insulator will typically be open, permitting the brushes to engage the bus bars. A polarizer extending from one side of the trolley, in conjunction with a polarizing lip depending downward from one side of the housing, may interfere with each other to resist insertion of the trolley into the conductor bar track in an incorrection orientation.
To install the trolley, a power cord for providing electrical power to a desired article of electric equipment may first be installed within the trolley. The release levers are manipulated to retract the bearings, and the trolley is inserted into the housing. The release levers are again manipulated to extend the bearings, securing the trolley within the housing. At this point, the bearings are free to roll along the shelves, and the bus bars are spring-biased upward to contact the conductor bars. Electrical current may thereby flow from the bus bars, through the brushes, to the power cord, and finally to the electrical equipment. Pulling chains may then be installed on the pulling loops to facilitate movement of the trolley within the system as desired.
A continuously installable/removable trolley for conductor bar systems is particularly useful for moving electrical equipment such as overhead cranes, aircraft hanger doors, and storage and retrieval systems.